Fat Sass Switchback Challenge
Millburn, United States • 5 Oct 2025
Event overview
The Fat Sass Switchback Challenge is a trail running fundraising event held in Millburn, NJ at the Locust Grove Picnic Area in South Mountain Reservation. Race formats offered are:
- 5K - three laps of the 1-mile loop
- 3HR - as many 1-mile loops as possible within three hours
- 6HR - as many 1-mile loops as possible within six hours
The event raises funds for Bigger Than The Trail, a 501(c)(3) organization that provides free therapy services. This is a FAT (S)ASS event: organizers provide water and bibs only. No swag, medals, or awards are provided. The event does not offer refunds or deferrals for the Fat Sass events.
Course and logistics
The course is a 1-mile loop with 300 ft of elevation gain: about 0.5 mile up the Lenape Trail and 0.5 mile down switchbacks. About 95% of the loop is technical, rocky trail and about 0.20 mile is on pavement. A GPX file is available on the event website.
Participants are responsible for tracking their own laps on large loop boards at the start/finish; 5K finishers also record their finish time on the boards using the race clock. Only water is provided; participants should bring their own food and electrolyte supplies. Parking is recommended across the street at the Millburn Public Library lot or the NJ Transit train station lot. Dogs are not permitted on the trails; spectators’ dogs must be leashed. Pacers are allowed only for participants aged 60 or older and for athletes with disabilities. Visit the organization's website for the most recent information.